c++ - 如何在 switch 语句内部或外部使用 if 语句 (C++)

Question

我是编程新手，正在做从这里找到的编码挑战 http://www.cplusplus.com/forum/articles/12974/ .我无法通过谷歌搜索找到我的具体问题的答案，这是我第一次在这里发帖，所以如果我违反了任何准则，我深表歉意!我正在研究让用户选择一个数字来选择他们最喜欢的饮料的挑战。

我刚刚了解了 switch 语句，我命名了 5 个案例，不包括默认情况。我试图弄清楚如何将 if 语句合并到 switch 语句中(如果这可能的话)，或者它可能是我正在寻找的 for 循环？我不确定，但我愿意了解它是什么。我正在尝试这样做，以便如果用户没有输入有效的案例编号并且它将变为默认值。 (例如:1、2、3、4 或 5 以外的任何数字)我希望用户在遇到默认大小写时再次尝试输入正确的数字。

这是我的代码

#include <iostream>
#include <string>
#include <iomanip>
using namespace std;

int main()
{
    int choice;

    cout << "Choose your beverage of choice by number: " << endl;
    cout << "1. Coke" << endl;
    cout << "2. Dr. Pepper" << endl;
    cout << "3. Sprite" << endl;
    cout << "4. Iced Tea" << endl;
    cout << "5. Water" << endl;
    cout << '\n';
    cin >> choice;
    cout << '\n' << "Choice entered: " << choice << endl;
    cout << '\n';
    switch (choice)
    {
        case 1 : cout << "You have chosen Coke." << endl;
        break;
        case 2 : cout << "You have chosen Dr. Pepper." << endl;
        break;
        case 3 : cout << "You have chosen Sprite." << endl;
        break;
        case 4 : cout << "You have chosen Iced Tea." << endl;
        break;
        case 5: cout << "You have chosen Water." << endl;
        break;
        default: 
        cout << "Error. Choice Not valid. Money returned." << endl;
        break;

    }

    system("pause");
    return 0;
}

Answer 1

I am trying to make it so that if the user does not enter a valid case number and it goes to default. (ex: anything other than 1, 2, 3, 4, or 5) I want the user to make another attempt at entering a correct number when it hits the default case.

实现这一点的一种方法是在接收用户输入和 switch 语句的代码块周围放置一个 do-while 循环。

int main()
{
   bool isValidChoice = true;
   do
   {
      // Reset when the loop is run more than once.
      isValidChoice = true;

      int choice;

      cout << "Choose your beverage of choice by number: " << endl;
      cout << "1. Coke" << endl;
      cout << "2. Dr. Pepper" << endl;
      cout << "3. Sprite" << endl;
      cout << "4. Iced Tea" << endl;
      cout << "5. Water" << endl;
      cout << '\n';
      cin >> choice;
      cout << '\n' << "Choice entered: " << choice << endl;
      cout << '\n';
      switch (choice)
      {
         case 1 :
            cout << "You have chosen Coke." << endl;
            break;

         case 2 :
            cout << "You have chosen Dr. Pepper." << endl;
            break;

         case 3 :
            cout << "You have chosen Sprite." << endl;
            break;

         case 4 :
            cout << "You have chosen Iced Tea." << endl;
            break;

         case 5:
            cout << "You have chosen Water." << endl;
            break;

         default: 
            cout << "Error. Choice Not valid. Money returned." << endl;
            isValidChoice = false;
            break;
      }
   } while ( !isValidChoice );
}